foo{path=~"^foo$"}[5m] or
#          ^ @regex
foo{path!~"[a-zA-Z0-9]{1,3}"}[5m] or
#          ^ @regex
foo{path="/api/users/{userId}"}[5m] or
#         ^ @!regex
foo{path!="/api/users/{userId}"}[5m]
#          ^ @!regex

# vim: ft=promql